Variable front axle valve

ABSTRACT

A front axle valve automatically effective to vary the pressures supplied from a fluid pressure brake system to the front axle brakes and having means for varying the relationship of system to brake pressure.

0 United States Patent 11 1 3,653,721 Klimek [451 Apr. 4, 1972 54]VARIABLE FRONT AXLE VALVE 3,492,052 1/1970 Klimek ..303/6 c 3,499,688 3/1970 [72] Inventor. Boleslaw Khmek, Des Plames, Ill. 3,526,437 9/1970 73Assignee; Bel-g Mf & Sales Co" Des plaines, [11 3,547,498 12/1970 Bueler..303/6 C [22] Filed July 1970 Primary Examiner-Duane A. Reger [2]]Appl. No.: 58,551 Att0rneyParker,Carter&Markey [57] ABSTRACT [52] U.S.Cl. "303/6 C, 137/102 5 1 1111. C1 ..B60t 15/36, 605d 1 1 /03 A fromaxle valve automatically effective to y the pressures 53 Field of Search..137/102; 188/151 A; 303/6 c, supplied from a fluid Pressure brakeSystem to the from axle 303/5 R, 59 2 brakes and having means forvarying the relationship of system to brake pressure. [56] ReferencesCited 5 Claims, 2 Drawing Figures UNITED STATES PATENTS 3,420,256 1!1969 Kobnick ..303/6 C UX i/ 33 i4 2] i4 )7 z Z/\ i .1 [f If g Z Z l rZ7 I Q l 7 4 i 7 VARIABLE FRONT AXLE VALVE OBJECTS OF THE INVENTION tionof system pressure as brake application continues and thereafter toagain supply full system pressure to the front axle brakes.

Another purpose is to provide a valve of the type described and havingmeans adjustable to vary the timing of increased pressure deliverythrough the valve of the invention.

Other purposes may appear from time to time during the course of thespecification and claims.

BRIEF DESCRIPTION OF THE DISCLOSURE The invention is illustrated more orless diagrammatically in the accompanying drawings wherein:

FIG. 1 is a side elevation in cross section; and

FIG. 2 is a diagrammatic chart illustrating the operation of theinvention.

Like parts are indicated by like numerals throughout the specificationand drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings,and particularly to FIG. 1, the numeral 1 generally designates ahousing. An inlet port is shown at 2. An outlet port is shown at 3, itbeing understood that an outlet 3 would normally be provided for each ofthe front axle brakes and that the fluid pressure brake system of thevehicle would communicate with inlet 2.

Housing 1 defines an inner chamber A with which inlet 2, outlet 3 and anexhaust outlet 4 communicate. A differential piston 5 is reciprocal inchamber A having its major diameter portion 6 presented to outlet 3 andits smaller, cup-shaped diameter portion 7 presented to inlet 2.Floating within piston 5 is a dual-headed valve member 8 having a head 9positioned for closing exhaust outlet 4 and urged thereagainst bycircumferentially spaced, depending legs 10 of piston 5. A stem 1 l ofmember 8 extends through aperture or passage 12 formed in piston 5 forcommunication of inlet 2 with outlet 3. The opposite valve head 13 ofmember 8 rides on circumferentially spaced guide vanes 14 and is inposition to close the passage or aperture 12 in piston 5 to closecommunication between inlet 2 and outlet 3.

A piston 15 has a major diameter slidable within an expanded portion ofchamber A, the major diameter of piston 15 being greater than eitherdiameter of piston 5 and being presented to inlet 2. Piston 15 carriescircumferential ringlike axial extension or sleeve 16 within which thesmaller diameter of piston 5 sealingly slides and which is in positionto engage the larger diameter 6 of piston 5. A spring 17 engages aportion of piston 15 and piston 5 to urge the same in oppositedirections.

Piston 15 carries a central web or spider 20 through which air may passfrom inlet 2 to passage 12 and which carries a central hub 21. It willbe observed that spring 17 seats against the radially disposed legs ofweb 20. A bolt 22 extends through hub 21 and has its head engaging theundersurface of hub 21, as the parts are shown. A threaded portion 23 ofbolt 22 threadably engages a spring pressure plate 24 slidable in.

chamber A and having radial extensions slidable within circumferentiallyspaced guide vanes 25. A spring retainer plate 26 has its peripheralportion clamped between portions of housing 1, as indicated at 27. Theplate 26 is centrally apertured for movement therethrough of web 20. Aspring 30 of substantially greater force than that of spring 17 has itsopposite ends in engagement with plates 24 and 26 to urge piston 15 in adirection away from piston 5.

Bolt 22 has its distal end 31 received within a plug 32 rotatable in anupper portion of housing 1. Plug 32 has a tool-engageable head 33positioned externally of housing 1. Lock means 34 is provided to insureagainst unintentional rotation of plug 32.

The use and operation of the invention are as follows:

The basic operation of the valve of the invention may be fullyunderstood by reference to my U.S. Pat. No. 3,492,052, entitled FrontAxle Valve and issued Jan. 27, I970. F undamentally, system pressuredelivered at inlet passes through passage 12 and outlets 3 to the frontaxle brakes of the vehicle. Full system pressure is thus transmitted inthe initial portion of brake application, e.g. that portion required tomove the brake shoes into engagement with the brake drums. Thereafter,as indicated by the line XY in FIG. 2, a decreasing portion of pressuredelivered at inlet 2 is delivered at outlet 3 to the front axle brakes,the increasing system pressure building beneath the larger diameter ofpiston 5 presented to outlet 3 and causing movement of piston 5 andresulting diminution of passage 12. At a predetermined point theincreased system pressure delivered at inlet 2 becomes effective againstthe larger piston 15 to move it downwardly and again move piston 5 awayfrom valve head 13 to again open passage 12 and to provide an increasingproportion of system pressure to outlets 3 and to the front axle brakes.

It will be observed that movement of piston 15 toward outlet 3 andpiston 5 is restricted by spring 30, a spring of somewhat greater forcethan that of spring 17. In the valve of U.S. Pat. No. 3,492,052,referred to above, the point at which increasing pressures are deliveredthrough outlets 3 and the point at which full system pressure is againdelivered through the valve of the invention was fixed and is indicatedin FIG. 2, for example, by the solid line YZ. In the present inventionthe spring 30 may be prestressed by rotation of head 33, plug 32 andbolt 22 to draw plate 24 downwardly, as the parts are shown in thedrawings, and thus to compress spring 30 between plate 24 and fixedretainer or abutment plate 26. Thus the pressures passing throughhousing 1 and the relationships and timing of changes from full todecreasing to increasing to full system pressures may be modulated asdesired as indicated by the dotted lines in FIG. 2, movement of plate 24toward abutment 26 being effective to prestress spring 30 and thus tomove the line YZ to the right in reference to FIG. 2.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A valve including a housing, an inlet, an outlet, a differentialpiston reciprocal in said housing between said inlet and said outlet,said piston having a smaller surface presented to said inlet and alarger surface presented to said outlet, a passage through said pistoncommunicating said inlet and outlet, a valve element positioned tocontrol said passage, yielding means urging said differential pistontoward passage-open position, and a second piston, said second pistonhaving a surface presented to said inlet and larger than either surfaceof said differential piston, said second piston having a portionengageable with said differential piston to urge said differentialpiston toward said passage-open position in response to delivery offluid pressure at said inlet above a predetermined level, and meansavailable externally of said housing for varying the reaction of saidsecond piston at predetermined levels of fluid pressure at said inlet.

2. The structure of claim 1 wherein said last-named means includes aspring urging said second piston away from said differential piston andmeans for prestressing said spring.

3. The structure of claim 2 wherein said prestressing means includes aplate slidable in said housing and means rotatably engaging said plateand effective to urge said plate against the action of said spring tostress the same.

4. The structure of claim 1 wherein said last-named means includes aspring having one of its ends engaging an abutment fixed in saidhousing, a plate carried by said piston and engaging the opposite end ofsaid spring and means for moving said plate toward said abutment tocompress said spring.

5. The structure of claim 1 wherein said yielding means engages saiddifferential and said second piston to urge said pistons in oppositedirections.

1. A valve including a housing, an inlet, an outlet, a differentialpiston reciprocal in said housing between said inlet and said outlet,said piston having a smaller surface presented to said inlet and alarger surface presented to said outlet, a passage through said pistoncommunicating said inlet and outlet, a valve element positioned tocontrol said passage, yielding means urging said differential pistontoward passage-open position, and a second piston, said second pistonhaving a surface presented to said inlet and larger than either surfaceof said differential piston, said second piston having a portionengaGeable with said differential piston to urge said differentialpiston toward said passage-open position in response to delivery offluid pressure at said inlet above a predetermined level, and meansavailable externally of said housing for varying the reaction of saidsecond piston at predetermined levels of fluid pressure at said inlet.2. The structure of claim 1 wherein said last-named means includes aspring urging said second piston away from said differential piston andmeans for prestressing said spring.
 3. The structure of claim 2 whereinsaid prestressing means includes a plate slidable in said housing andmeans rotatably engaging said plate and effective to urge said plateagainst the action of said spring to stress the same.
 4. The structureof claim 1 wherein said last-named means includes a spring having one ofits ends engaging an abutment fixed in said housing, a plate carried bysaid piston and engaging the opposite end of said spring and means formoving said plate toward said abutment to compress said spring.
 5. Thestructure of claim 1 wherein said yielding means engages saiddifferential and said second piston to urge said pistons in oppositedirections.